This invention relates to full-wave diode bridge rectifiers. More particularly, it is concerned with methods of fabricating full-wave diode bridge rectifiers in monolithic integrated circuit structure.
Frequently electronic circuitry which may be amenable to fabrication in monolithic integrated circuit structure requires a full-wave diode bridge rectifier. In order to utilize fully the advantages of extremely small size and manufacturing efficiency obtained with monolithic integrated circuits, it is desirable that the diode bridge also be fabricated as an integrated circuit rather than as an assembly of individual components. In many instances it is particularly desirable that the diode bridge be fabricated within the same semiconductor chip as the circuitry with which it is associated.
Previously available integrated circuit chips which included diode bridge rectifiers employed conventional junction diodes. However, parasitic transistors are inherently present when junction diode bridges are fabricated within a chip, leading to undesirable current flow and consequent low efficiency. Although by incorporating diffused guard rings in the structure the loading effect of the parasitic transistors can be reduced, large surface areas of a chip are required in order to obtain significant improvement in efficiency. As is well-understood in the semiconductor art larger surface areas make a device more expensive.